From Eclipsepedia

The JAXB compiler can be run to generate JAXB annotated Java classes from an XML Schema. The following are examples of the most common usage:

<ECLIPSELINK_HOME>/eclipselink/bin/jaxb-compiler.sh example.xsd -d targetDirectory
<ECLIPSELINK_HOME>\eclipselink\bin\jaxb-compiler.cmd example.xsd -d targetDirectory

For more detailed compiler options:

<ECLIPSELINK_HOME>/eclipselink/bin/jaxb-compiler.sh -help
<ECLIPSELINK_HOME>\eclipselink\bin\jaxb-compiler.cmd -help

See EclipseLink Support for JAXB in the EclipseLink User's Guide for more information.